‎Let $S$ be a set of $n$ points in the plane‎, ‎$\nabla(S)$ the set of all simple polygons crossing $S$‎, ‎$\gamma_P$ the maximum angle of polygon $P \in \nabla(S)$ and $\theta =min_{P\in\nabla(S)} \gamma_P$‎. ‎In this paper‎, ‎we prove that $\theta\leq 2\pi-\frac{2\pi}{r.m}$ where $m$ and $r$ are the number of edges and inner points of the convex hull of $S$‎, ‎respectively‎. ‎We also propose an algorithm to construct a polygon with the upper bound on its angles‎. ‎Constructing a simple polygon with the angular constraint on a given set of points in the plane can be used for path planning in robotics‎. ‎Moreover‎, ‎we improve our upper bound on $\theta$ and prove that this is tight for $r=1$‎.

Abstract Access to information is a fundamental element in research and production of science process, as well as one of the metrics of development. So, the awareness and use of communicational and informational networks, as well as their related technologies could be really necessary. In this connection, internet, web and related techniques, such as RSS (Really Simple Syndication, Rich Site Summary, or RDF Site Summary) is one of these technologies which appeared on many websites, weblogs and databases, in recent years and became the most expanded and suitable tool for making awareness. Obviously, this technology allows the librarians and information scientists to find access to the existential information on websites, weblogs and databases, in order to improve their commercial, economical, educational, research, social and cultural relations. More over, using this technology can make users to access to their information by themselves, and to fulfill their informational needs. This technology through its own language programming can show the latest information and become up to date by adding new information. RSS is a simple and quick method for current awareness, new book list, reference services, education and communication with users, which should not be ignored by librarian in libraries and information centers.Therefore, we tried first to give a definition of RSS feed as well as to present its advantages for application; then we try divide RSS readers into two main groups; web based and special software based, with some examples of each group. At the end, we suggest that for better understanding and also for providing appropriate and suitable information services for users, this technique (RSS Feed) and its facilities should not be ignored by librarians in the libraries and information centers.

Background: The aim of this study was to evaluate the outcome and survival in patients with RCC treated with non-hilar clamping simple enucleation. Methods: In this case series study, all patients in Hashemi Nejad Hospital in Tehran undergone non-hilar clamping simple enucleation surgery in the years 1383 to 1393 by RCC T1 enrolled the study. Exclusion criteria included the presence of multi-focal RCC, synchronous mass in patients, the existence of positive lymph nodes before or during surgery and radical nephrectomy due to past RCC. 134 patients undergoing partial nephrectomy in tumors T1 (T1a, T1b) studied, 9 patients has not completed the follow up and 10 patients had oncocytoma and angiomyolipoma excluded the study. 115 patients with RCC pathology who undergone non-hilar clamping Simple Enucleation were examined. Results: In this case series study, 115 patients with pathologically confirmed RCC were evaluated on the basis that 70patients were male and 45 were female. Patients have ranged in age from 20 to 75 years old and 51. 28 year. Average figure of 97% progression free survival at three-year and five-year study was 89%. Also three-year study of cancer specific survival at five years was 100% and 95% respectively. Patients who have relapsed 2 female and 2 were male. The recurrence was not significantly associated with gender (p= 0. 511). Also 2 patients had recurrence of the left kidney and 2 were all right and there was no statistically significant difference (p= 0. 643). Every 4 patients recurrent disease have T1b the difference was significant (p= 0. 026). Also patients had recurrence of grade 2 to grade 1 patients have high grade recurrence was observed (p<0. 001). No significant difference was found between GFR before and 3 months after surgery (p= 0. 802) and a biopsy of the tumor bed margins were negative in all cases. Conclusion: Non-clamping SE in patients with T1 renal masses is similar to partial nephrectomy is onchologic results. In this study, recurrence was higher in patients with T1b tumors that appear in determining treatment and close follow-up T1 b should be more comprehensive criteria. Non clamping SE preserving kidney function is a good choice in the treatment of T1 tumors. Non clamping SE more complications following surgery and that could be more widely used.

In this note, we introduce the concept of topologically simple semihypergroup and determine when topological simplicity of a complete subsemihypergroup of a semihypergroup implies its simplicity from algebraic point of view.

Background and Aims: According to the common application of non-metal prefabricated posts in dentistry and lack of enough information about the stress distribution in the root canal walls by these posts, this study was performed to compare the effect of two simple taper and double taper posts on the stress distribution on root canal walls by photo elastic method.Materials and Methods: The design of this study was experimental in photoelastic system. The posts, used in this investigation, were double taper and simple taper fiber posts with 0.9 mm diameter and 20 mm length and epoxy resin. First two photo elastic models with tooth dimensions were fabricated and the posts were placed inside the model. Then the core of the each post was fabricated on the model. Each models were loaded in polariscope and the formed fringe order colored ring were photographed.Results: In 100 N, 90 degree angle loading in cervical and apical fringe order showed 2.50 and 1.39 in simple taper posts and 1.39 and 2.35 in double taper post. In 150 N, 30 degree angle loading in cervical and apical fringe order showed 4 and 2.65 in simple taper posts, and 4 and 2.5 in double taper post.Conclusion: In the vertical and oblique loads, double taper fiber post showed better stress distribution than that of simple tapered posts.

The exhaust gases of gas turbine power plant carry a significant amount of thermal energy that is usually expelled to the atmosphere; this causes a reduction in net work and efficiency of gas turbine. On the other hand, the generated power and efficiency of gas turbine plants depend largely on the temperature of the inlet air, So that they both increase as the inlet air temperature decreases. The mentioned two problems can be solved by installing an absorption refrigeration cycle (ARC) at gas turbine inlet, working with thermal energy of exhaust gases. In this research, effect of inlet air cooling on gas turbine performance is studied. The work shows that, the net work and the efficiency will increase by 6-10% and 1-5% respectively for every 10°C decrease of inlet temperature. Since, coefficient of performance (COP) of ARC is low, with high pressure ratios in simple gas turbine (SGT) and with low pressure ratios in regenerative gas turbine (RGT), thermal energy of exhaust gases can not supply all the needed thermal energy for refrigeration cycle. The results show that, when an ejector is included in refrigeration cycle, the need for external energy source required for refrigeration cycle is reduced.

Background: Maritime transport from the beginning of human history, has played a fundamental role in shaping human societies and their economic development. In this era the communication arteries are the foundation of any country's economy. Due to the development of the necessary ports, coastal dredging activities in Iran had a growing trend during over the past two decades. However, from an environmental perspective less attention has been made particularly for the management of dredged material.. In this paper, the environmental risks of dredging operations were identified and ranked at Bandar Imam Khomeini.Methods: The Delphi questionnaires were applied in order to initially create the important risk factors associated with dredging operations.. Then, multi-criteria decision making techniques were developed to calculate the likelihood of weighted index entropy measures, severity and likelihood of each risk has been detected, identified and prioritizes as significant risks using the Simple-additive-weighting (SAW) technique.Results: The results show that the size and concentration of petroleum hydrocarbons and heavy metals increased in aquatic organisms tissue and are noted as important risks as the first and second stress in the aquatic habitats. Creating of disorder in the context of the nature of bed sea during the dredging operations has also been ranked as the third factor.Conclusion: Primarily of dredging operations will ultimately lead to ecological imbalance, environmental risks and leads to disturbance in the location of the dredging.